This is how London is expanding one of its busiest Underground stations without anybody knowing

Bank is one of London's busiest stations, averaging around 450,000 commuters per day.

The upgrade is costing over £600 million, excavating over 600 metres of new tunnels.

The Bank station capacity upgrade is expected to be finished in 2022.

One of London's busiest stations is expanding, and most Londoners have no idea.

Business Insider was given an exclusive tour of the Bank Station capacity upgrade project, which is creating over 600 metres of new tunnels and receiving a bigger, brand new station entrance.

Bank is located right in the centre of the city district of London and receives around 450,000 commuters a day, leaving the station heavily congested during peak times. This upgrade is meant to relieve some of that congestion, making it a smoother commute for passengers.

All this is being done alongside the current underground tunnel, without disrupting commuters and normal underground operations, making it an impressive project.

The upgrade is costing over £600 million and expected to be finished in 2022.